#include <stdio.h>
#include <stdlib.h>

int main()
{int n;
int i,m;
int t=1;
double f=0.00;
double sum=0.00;
   scanf("%d",&n);

   for(m=1;m<=n;m++)
    {t*=m;
    f=1.0/t;
    sum+=f;}


   printf("%.5f",sum);
    return 0;
}
